Welcome back to "Gma," 7:43. And a safety warning on cell phones which can heat up dangerously. Getting a lot of attention after a Texas teen said her phone caught fire under her pillow while she was sleeping. Mara has her story. Reporter: They suspect the phone's battery caused the fire. We told you about the dangers of lithium ion batteries that can get hot and explode. 13-year-old got an unexpected wakeup call a few hours after falling asleep with her cell phone under her pillow. I smelled a strong burning smell zblp. Reporter: It was a terrible scare after her schb caught fire. There's a hole in my mattress. It was charred. Reporter: Luckily ariele says she was not hurt. But in addition to the damage to her bed, the phone melted and was destroyed. It's surreal to see there's a shouldering fire in your child's bedroom. Made me feel sick that it happened. Reporter: She says she was using a replacement lithium ion battery and suspects it overheated. At least one major manufacturing warns that covering it with bedding can cause a fire or explosion. While it's rare, they can happen. Last month, "Gma" investigates reported on lithium ion batteries. They're capable of putting a lot of energy in a small package. Reporter: They can overheat, in this case, over 350 degrees. And in some cases, exploding. Keep them away from metal, like coins, keys or jewelry, and try not to drop your device. Treat it properly. Reporter: It's a lesson she says she's learned after the close call. I've learned not to keep my phone in my bed. Just put it next to you on the floor or like a night stand or something. Reporter: Now as for her habit of sleeping with her phone, it's very common. A survey last year found 63% of those 18 to 29 say they sleep with their phone or tablet in the bed, and 29% of those 30 to 44 do it. I fall asleep with it in the bed. I fall asleep with it accidently in my hand. You should the covers? Put the phone down. Yeah. Step away from the phone. I would say I -- my kids are watching, a little healthy fear of your cell phone so it's not attached to your body is not bad. Knowing it can explode. Thank you so much, Mara. Coming up, why eating before bed might actually be good for

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